Son Doong Cave, Phong Nha-Ke Bang National Park

Marvel at underground vegetation and impressive stalagmite towers at Son Doong Cave, a huge cave system featuring its own jungle and a river. Over 8.8 km (5.5 mi) long, the cave was touted as the biggest in the world. Camp on the rough sandy beach on the banks of an underground river and admire the shades of light coming from large holes above the ground. Set in Phong Nha Ke Bang National Park, the cave was discovered by a local in 1991, but was not seriously explored until 2009. Explore ancient limestone walls created 250 m years ago and abseil into a true underground paradise with fabulous rock shapes fringed with vegetation. Plan to visit Son Doong Cave and other customer-reviewed, writer-recommended Phong Nha-Ke Bang National Park attractions using our Phong Nha-Ke Bang National Park holiday planner.

I've lived in Vietnam for years and have explored up and down some of the most exotic places on in Vietnam, on the continent and across world.
This, by far, bar none, is an experience of a lifetime. I would imagine that in the last hours of my life I would think about Son Doong as one of those experiences that made life worth it.
Clearly the poor reviews are written by people who have not been inside of the cave and would value a half-month's salary over one of life's great experiences.
I was one of the first 500 people in the cave back in April of 2015, wildly enough on the 40th anniversary to the day of the end of the Vietnam War and the reunification of the north and south. Knowing this region was one of the most heavily bombed parts of the country, I as an American was overwhelmed standing inside of one of God's greatest sculptures inside of a country that was a sworn enemy a generation ago.